OT: annoying British girl says Windows 7 is "miles simpler(!)"

So there's that Microsoft commercial where the British chick says that Windows 7 is "miles simpler(!)" in a British accent ("my-els simplah") - which has now become a catch phrase for me. She, like many others, claims that Windows 7 was her idea. But then at the end of the commercial she seems to say enthusiastically to the person driving the car she's in, "On witch driver!" What the F is that? Are British people typically driven around by witches? Does anyone out there know what the F that woman is saying? I don't know where else to turn to figure this out...